When calcium reacts with fluorine in a synthesis reaction, which compound is produced? Complete the equation: Ca + F_2 → ________

• A. Ca_2F
• B. CaF_2
• C. Ca_2F_2
• D. CaF

Answer: (B)

Verified step by step guidance

1. Step 1: Identify the elements involved and their typical ionic charges. Calcium (Ca) is an alkaline earth metal that typically forms a +2 charge (Ca^{2+}), and fluorine (F) is a halogen that typically forms a -1 charge (F^{-}).
2. Step 2: Write the formula for the compound by balancing the total positive and negative charges so that the compound is electrically neutral. Since calcium has a +2 charge and fluorine has a -1 charge, two fluorine ions are needed to balance one calcium ion.
3. Step 3: Combine the ions in the ratio that balances the charges: one Ca^{2+} ion and two F^{-} ions, resulting in the formula CaF_2.
4. Step 4: Write the balanced chemical equation for the synthesis reaction. Calcium reacts with fluorine gas (F_2) to form calcium fluoride (CaF_2). The balanced equation is: Ca + \frac{1}{2}F_2 → CaF_2. To avoid fractions, multiply the entire equation by 2 to get: 2Ca + F_2 → 2CaF_2.
5. Step 5: Confirm that the formula CaF_2 matches the correct compound produced in the reaction, which is calcium fluoride, consistent with the charges and the balanced equation.